What is this in java

What is this keyword?

The keyword this can only be used inside a method and represents a reference to the current object.

Usage of this keyword

1. Access member variables, distinguish member variables and local variables

2. Access member methods

3. Access the constructor method

4. Return a reference to the current object

5. Pass the reference to the current object as a parameter to other methods

The usage is as follows: Test0505.java

class Person{
	private String name;//成员变量
	private int age;
	Person(){}
	Person(String name){//局部变量
		this.name=name;//1.用"this.成员变量名称"和重名的局部变量区分开来
	}
	Person(String name,int age){
		this(name);
		this.age=age;
	}
	String getInfo(){//成员方法
		return "姓名：" + name + "\n年龄：" + age;
	}
	void print(){
		System.out.println(this.getInfo());//2.用"this.成员方法名"访问成员方法。
		System.out.println(getInfo());//这种情况this关键字一般不写，让编译器自动添加。
	}
}
public class Test0505{
	public static void main(String[] args){
		Person p=new Person("张三",33);
		p.print();
	}
}

class Person{
	private String name;
	private int age;
	Person(){}
	Person(String name){//不含this()的构造方法
		this.name=name;
	}
	Person(String name,int age){//在构造方法内调用另一个构造方法
		this(name);//3."this();"访问构造方法必须放在构造方法的第一行
		this.age=age;
	}
	String getInfo(){
		return "姓名：" + name + "\n年龄：" + age;
	}
	void print(){
		System.out.println(this.getInfo());
	}
}
public class Test0505{
	public static void main(String[] args){
		Person p=new Person("张三",33);
		p.print();
	}
}

class Leaf{
	private int i=0;
	Leaf increment(){
		i++;
		return this;//4.返回对当前对象的引用。
	}
	void print(){
		System.out.println("i="+i);
	}
}
public class Test0505{
	public static void main(String[] args){
		Leaf x=new Leaf();
		x.increment().increment().increment().print();
	}
}

class Person{
	void eat(Apple apple){
		Apple peeled=apple.getPeeled();
		System.out.println(peeled);
	}
}
class Apple{
	Apple getPeeled(){
		System.out.println(this);//输出对当前对象的引用。
		return Peeler.peel(this);//5.将对当前对象的引用作为参数传递给其他方法。
	}
}
class Peeler{
	static Apple peel(Apple apple){
		return apple;
	}
}
public class Test0505{
	public static void main(String[] args){
		Apple a=new Apple();
		System.out.println(a);
		new Person().eat(a);
	}
}

Recommended tutorial: javaQuick Start

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